Method for identifying pressure sensors, and associated system

Abstract

The present invention relates to a method for identifying pressure sensors, notably pressure sensors for an electronic tire pressure monitoring system for a motor vehicle, said sensors (9, C1, C2, C3, C4) comprising at least a module for emitting and receiving data, said method comprising: - emission (S1) of a sensors activation signal; - receipt (S2) of signals coming from at least two different sensors after they have been activated; - attenuation and amplification (S3) of the signals received; - determination (S4) of a value indicative of the power of the signal for each of the signals received; - identification (S5) of the spatial position of at least one sensor on the basis of the values indicative of the power of said signals received. The present invention also relates to a device configured for implementing said method.

Description

[0001] The present invention relates to the field of sensors and in particular to a method of identifying said sensors allowing them to be differentiated and located, as well as to a device allowing the implementation of said method.

[0002] More particularly, the present invention is advantageously applicable to pressure sensors housed in the tires of a motor vehicle, sensors generally associated with the computer of a motor vehicle to which said sensors transmit data.

[0003] The entire sensor-on-board computer assembly is thus designated under the term "electronic tire pressure monitoring system" (or in English "Tire Pressure Monitoring System" with the associated acronym "TPMS").

[0004] Each tire pressure sensor is typically equipped with a radio frequency transmitter to allow data transmission to the vehicle's onboard computer. The onboard computer, receiving the data from the sensors, can then alert the vehicle's user if a tire were to puncture or deflate, posing a safety risk.

[0005] However, the pressure sensor housed in the wheel is not usually removable, so changing a wheel implies changing the sensor, the new sensor is then no longer detected by the vehicle's on-board computer.

[0006] Therefore, when changing tires, it is necessary to pair (or associate) the sensors housed in the new tires with the vehicle's on-board computer.

[0007] This pairing is done using a dedicated learning device (generally referred to in English as a "TPMS tool"), said device being configured to activate the sensors, retrieve and record the relevant data emitted by the sensor, such as the sensor identifier, and transmit it to the on-board computer, so that the latter can detect and locate the sensors housed in the newly installed tires and can capture the signals, in order to warn the user in the event of a drop in pressure in one of said tires.

[0008] Patent documents WO2019243374 and FR2826731 describe techniques for identifying the position of sensors housed in vehicle tires. However, these techniques are relatively complex and expensive to implement.

[0009] However, in some vehicles, such as heavy goods vehicles or buses, the wheels are mounted in pairs at each end of the axles; these are called twin wheels.

[0010] In twin wheels, the two associated sensors are sometimes very close, making it difficult to differentiate emissions from the sensors (both when stationary and during vehicle operation) without implementing particularly complex and expensive coding and identification techniques.

[0011] For example, during the learning phase—that is, the phase where sensor IDs are retrieved and communicated to the vehicle's onboard computer—the sensors are activated sequentially in a predetermined order so that the onboard computer can identify and associate the sensors with each of the vehicle's wheels. However, simultaneous activation of several sensors can occur unintentionally when they are queried by the operator using their sensor activation device (such as the learning device). The operator cannot then determine whether the sensor located in the outer wheel or the sensor located in the inner wheel is being activated.

[0012] The problem of simultaneous activation of multiple sensors also arises in factories, such as tire or automotive manufacturing plants, where it is necessary to activate sensors for testing, identification, and / or pairing with a vehicle's onboard computer. However, production lines in factories are often located very close to one another, and an activation signal emitted by a suitable device can trigger the activation of multiple sensors, hence the need to be able to identify or differentiate between activated sensors.

[0013] The problems outlined below led to the design of a method for identifying sensors housed not only in twin wheels, but also in separate wheels, as well as a device capable of implementing said method, such as a device for an electronic tire pressure control system of a motor vehicle.

[0014] The invention is thus a new method for identifying pressure sensors, in particular pressure sensors for an electronic tire pressure control system of a motor vehicle, said sensors comprising at least one data transmission and reception module according to the characteristics defined in the attached independent claim of method 1.

[0015] As explained above, the method according to the invention makes it possible to identify or discriminate sensors housed in twin wheels or in environments containing a plurality of sensors; it has the advantage of being simple to implement while being applicable in a wide variety of situations.

[0016] Indeed, prior attenuation before amplification allows us to "filter" some of the parasitic signals, but above all to make it easier to distinguish sensors that are very close to each other.

[0017] Depending on one possible characteristic, the representative power value of the signal is the gain value and / or the matching value of said signal. Each signal is, for example, characterized by a value representing the matching and / or gain undergone by each signal following its attenuation and amplification.

[0018] The representative power value is an indicator used to characterize signals. This value can be the gain, the matching value, or a combination and / or function of these parameters, depending on the sensor's position (stationary or moving) and its environment (parasitic signals, resonances, multiple signal reflections, etc.). The representative value, such as the matching value, is, for example, a function of the receiver's settings, these settings thus representing the signal's power.

[0019] According to another possible characteristic, the sensor activation signal is emitted at constant power.

[0020] Therefore, there is no need to include a component to vary the transmission power of the sensor activation signals, nor to have a power supply sized accordingly. This simplifies the design of the device implementing this process and reduces its cost.

[0021] According to another possible characteristic, there is reception of a plurality of signals from the same sensors.

[0022] Receiving multiple signals from the same sensor makes the sensor identification process more robust by enabling statistical analysis of the collected samples. Receiving multiple signals also allows for the selection of the signal with the highest power (or the highest representative value) for each sensor.

[0023] Generally, the reception of signals from sensors takes place over a set period of time, in order to receive several signals from the same sensors.

[0024] Each signal emitted by a sensor includes a sensor-specific identifier, allowing for the classification of received signals. Alternatively, the signal with the highest representative power value for each sensor is selected for this identification.

[0025] According to another possible characteristic, there is a comparison of the representative power values ​​of the plurality of signals received from at least a first and a second sensor, if the set of representative power values ​​of the signals from one of the sensors is always less than or greater than the set of representative power values ​​of the signals from the other sensor, then there is identification of the spatial position of at least one of the sensors based on the comparison of said representative power values ​​of the signals.

[0026] According to another possible characteristic, the received signals and / or representative power values ​​of the signals from the same sensors are averaged and compared with each other, in order to identify the spatial position of at least one of the sensors.

[0027] According to another possible characteristic, the distribution of representative power values ​​of the received signals is studied for each sensor in order to determine the most representative power value possible for each sensor. According to another possible characteristic, extreme representative power values ​​are suppressed to determine the most representative power value possible for each sensor.

[0028] According to another possible characteristic, the level of attenuation applied to the signals is variable, for example said level varies linearly over time and / or during a determined duration of reception of several signals.

[0029] The present invention also relates to a sensor activation device, in particular pressure sensors for an electronic tire pressure control system of a motor vehicle according to the characteristics defined in the attached independent device claim 9.

[0030] According to one possible characteristic, the sensor activation device is a learning device for an electronic tire pressure control system of a motor vehicle.

[0031] According to another possible characteristic, said sensors are pressure and / or temperature sensors housed in the tires of a motor vehicle.

[0032] According to another possible characteristic, each of the signals is characterized by a value representing the adaptation undergone by each of the signals following its attenuation and amplification, the representative power value of the signal being the adaptation value of said signal.

[0033] This process and device are very inexpensive and particularly easy to implement. They also do not require any modification of existing communication technologies between learning and / or activation devices and sensors.

[0034] The invention will be better understood, and other objects, details, features and advantages thereof will become more apparent from the following description of particular embodiments of the invention, given solely by way of illustration and not limitation, with reference to the accompanying drawings, in which: [ Fig. 1 ] is a schematic representation illustrating a sensor activation device according to the invention; [ Fig. 2 ] is an enlarged view of the device of the figure 1 ; Fig. 3 ] is a very schematic representation of the device of the figure 1 when used with one of the twin wheels; [ Fig. 4 ] is a flowchart detailing steps of the sensor identification process according to the invention.

[0035] There figure 1 is a very schematic representation of a sensor activation device 9, more particularly in the present example of a learning device 1 for an electronic system 3 for controlling the tire pressure of a motor vehicle 5 (said device 1 can also be referred to as a "valve activator" or "valve forcer").

[0036] The motor vehicle 5, on the one hand, is equipped with tires 7 in which are housed the sensors 9, such as pressure sensors, and on the other hand, includes an on-board computer 11 (also called electronic control unit and generally designated by the acronym "ECU").

[0037] Device 1 comprises a housing 13, for example made of plastic, a display device 15, a keypad 17, and an antenna 19 for transmitting a sensor activation signal, as well as an OBD (On-Board Diagnostic) port. This OBD port 21 is configured to allow, for example, the connection of device 1 to the on-board computer 11 of a vehicle, notably via an OBD cable.

[0038] There figure 2 Meanwhile, it is an enlarged and detailed view of the device of the figure 1 .

[0039] The said device 1 comprises the following: at least one sensor activation means 31, such as means for generating (continuous and / or modulated) sensor activation signals, said activation means 31 including the antenna 19 which in particular allows the generated signals to be propagated as best as possible to the sensors 9; a means for receiving signals 33 from the sensors, generally another antenna housed in the casing 13 and configured for example to receive signals in a frequency band between 300 and 500 MHz (the sensor emitting a signal after being activated by said activation means 31); an electronic unit 35 configured to store and / or process information carried by the signals emitted by said sensors 9 (and received via the receiving means 33);a means of communication 37 with an on-board computer 11 of a motor vehicle to transmit information from at least one of said sensors 9, information received via signals from said sensors 9. ;

[0040] The communication means 37 is, for example, an OBD module which includes an OBD communication management circuit 38 and the previously mentioned OBD connector 21. It should be noted that the management circuit 38 can also be integrated into the electronic unit 35. The device 1 also includes a battery 41 configured to power the various components.

[0041] It should also be noted that the said activation signals are electromagnetic signals, continuous or modulated, emitted by the activation means 31, which have, for example, a frequency of 125 kHz.

[0042] As illustrated in the figure 3 The device 1 must also be usable with trucks having dual wheels; therefore, the device 1 must be capable of identifying or differentiating the sensors housed in these tires arranged close to each other. In the example illustrated in the figure 3 The truck 6 includes several wheels, including axles 6a with twin wheels 7a and 7b at their ends, in which sensors C1 and C2 are housed, respectively. The truck may also include two other sensors C3 and C4, as illustrated in this diagram. figure 3 .

[0043] More specifically, the receiving means 33 of device 1 (means for receiving signals from the sensors) comprises at least three elements: a receiving antenna 33a, said antenna being configured to receive signals on the transmission frequency of said sensors and to transform said electromagnetic signals into electrical signals; an attenuator 33b, which is for example an electronic circuit or component allowing the amplitude of the received signal to be reduced, i.e. in this case, the electrical signal delivered by the antenna 33a); an amplifier 33c, which is for example an electronic circuit or component increasing the voltage and / or intensity of an electrical signal, in this case, the electrical signal attenuated by the attenuator 33b.

[0044] The electrical signals, obtained by successive attenuation and amplification, are then processed by the electronic entity 35 (reading, decoding, characterization, etc.).

[0045] Furthermore, it should be noted that the 33b attenuator is, for example, adjustable by level, such as 0 dB, -6 dB, -12 dB and -18 dB, or can be linearly variable between 0 dB and -18 dB.

[0046] Amplifier 33c is configured to automatically amplify the input signals to the desired level so that the output component (here, electronic unit 35) can process the amplified signal. Indeed, electronic unit 35 (the signal receiver in this case) only detects and processes signals with a minimum amplitude and a signal-to-noise ratio within a certain threshold.

[0047] The 33c amplifier or a third-party circuit therefore performs automatic gain control (also referred to by the acronym "CAG" in French or by the acronym AGC in English for "Automatic Gain Control") allowing automatic management of the amplifier's amplification and preventing saturation of the output and / or keeping the output level constant.

[0048] Thus, said device 1 emits an activation signal, for example, towards sensors C1 and C2 housed in twin wheels 7a and 7b of truck 6.

[0049] Sensors C1 and C2 are activated by receiving the activation signal and said sensors C1 and C2 then emit one or more signals in response.

[0050] Unfortunately, the activation signal emitted by device 1 can also activate one or more surrounding sensors, either other sensors on the truck, or sensors housed in the tires of vehicles in the vicinity.

[0051] Furthermore, sensors generally include a communication protocol limiting the collision of signals emitted by said sensors; this has the particular consequence that the closest sensor (the one theoretically receiving the activation signal first) will not necessarily emit first.

[0052] Furthermore, the sensors housed in twin wheels are very close to each other and in an environment with obstacles that can cause multiple reflections, this can result in variations in the power of the signals emitted by the sensors.

[0053] Subsequently, device 1 receives the various signals emitted by sensors C1 and C2. Preferably, device 1 is configured to receive all the signals emitted by the sensors for a predetermined duration. This predetermined duration is variable, but advantageously sized so that the device receives at least two signals from each of sensors C1 and C2.

[0054] The attenuator 33b is configured to attenuate "strongly" the signals received via the antenna 33a, the attenuation is for example set to attenuate the signals by -12 dB or -18 dB (respectively the power of the received signals is divided by 32 and 64).

[0055] This allows us to filter out parasitic signals, i.e. signals not coming from sensors C1 and C2 or resulting from multiple reflections (echo phenomenon).

[0056] Subsequently, the attenuated signals are amplified by amplifier 33c.

[0057] The 33c amplifier is configured to amplify input signals to a specific amplitude (or power) level. Therefore, the 33c amplifier will automatically amplify the signals to ensure they have the same amplitude and / or power at the output. The output characteristics of these signals depend, in particular, on the electronic components (sensors, etc.) downstream of the 33c amplifier and their configuration (i.e., the characteristics the signals must have to be processed by these electronic components).

[0058] Thus, the signals emitted by sensors C1 and C2, which have varying power signals, are attenuated identically and amplified to a fixed level (for example to obtain a specific signal-to-noise ratio).

[0059] Each amplified signal can therefore be characterized by a gain G that is proportional to the received signal power and the attenuation applied by attenuator 33b. The value of the gain G is thus representative of the signal power. This successive attenuation and amplification makes it easier to distinguish between two nearby sensors.

[0060] Indeed, if two nearby sensors each emit a signal A1 and B1 whose power difference is only 20%, power of A1 = 1 and power of B1 = 0.8; then amplification, without prior attenuation, results in low gain values ​​for each of the signals and differences between the gains for each of the signals which are not necessarily significant enough to be used in identifying the relative spatial position of the sensors with respect to each other.

[0061] For example, if the power of each signal must reach a value of 1.25, the gain GA1 applied to A1 is 1.25, while the gain GB1 applied to B1 is approximately 1.56; whereas if each signal undergoes a prior attenuation of -12 dB, the power of the attenuated signals A1 and B1 is approximately 0.0625 and 0.05 respectively, and their gain is 20 and 25 respectively. It can thus be seen that a high attenuation before amplification facilitates the identification of the sensors, based on the fact that the signal power emitted by the factor is proportional to its distance; the value of the signal gains allows the closest (or furthest) sensor to be determined.

[0062] Note that in the example below, the representative value of the signal power is the value of the gain applied to the signal, but this can be other characteristic quantities or a function depending on several parameters (such as attenuation, gain, etc.).

[0063] Thus, the identification process implemented by device 1, more specifically illustrated in the figure 4 includes at least the following steps: the emission S1 of a sensor activation signal; the reception S2 of signals from at least two different sensors following their activation, the attenuation and amplification S3 of the signals received from said two sensors; the determination of a representative value of the signal power (S4), such as the gain value G, for each of the received signals; the identification of the spatial position of at least one sensor S5 as a function of the representative power values ​​of said received signals.

[0064] It should be noted that: the sensor activation signal is preferably emitted at constant power and / or has a narrow emission cone; the received signals undergo identical attenuation.

[0065] Furthermore, the electronic entity 35 is configured to manage the reception time in order to receive a plurality of signals from the same sensors.

[0066] Furthermore, since each signal emitted by a sensor includes a sensor-specific identifier, the electronic unit 35 can classify the received signals according to their origin (i.e., the sensor that emitted the signal). Receiving several signals from the same sensor can, for example, allow the selection of the signal with the highest gain value G (or a representative power value) for comparison and identification of the relative spatial position between two sensors.

[0067] Thus, in parallel with the reception of said signals, the electronic entity 35 compares two by two the representative power value of the received signals, and makes it possible to verify that the representative power value of the signals emitted by a sensor is always less than or greater than the signals emitted by other sensors, if this is the case there is identification of the relative spatial position of at least one of the sensors which emitted a signal.

[0068] This additional step increases the chances of correctly identifying the spatial position of a sensor.

[0069] However, in order to further improve sensor identification, one can, for example, study the distribution, by sensor, of the representative power values ​​of the received signals, in order to determine a power value that is as representative as possible of the signal for each of the sensors.

[0070] Sensor signal values ​​are categorized by ranges of values, also known as classes in mathematics. This means that the extreme values ​​define classes into which the values ​​are distributed. It should be noted that classes can be defined with or without the same range (the range being the interval of values ​​defining each class).

[0071] Subsequently, the number of values ​​per class is determined and the class with the largest number of values ​​is selected (this is also referred to as the "modal class").

[0072] The interval containing the most values ​​is then considered the most probable, and the values ​​within this interval can be averaged to determine the most characteristic possible representative signal power value for each sensor. The characteristic values ​​for each sensor are then compared to determine the sensor closest (or furthest) to the receiving means 33.

[0073] It should be noted that whatever method is used, it can be generalized to n sensors, the comparison and ranking of representative power values ​​allowing the determination of the relative spatial positions of the sensors, with respect to each other, whose signals have been received.

[0074] In an embodiment not shown, the attenuation level, generated by the attenuator 33b, applied to the signals varies linearly, for example, over time. In this case, the representative signal power value is rather a value that is a function of the gain and the attenuation, such as a signal matching value.

[0075] The linear variation of attenuation also makes it possible to highlight transient phenomena that may affect the received signals and to eliminate these, in order to improve the identification of sensors.

Claims

1.

1. Method for identifying pressure sensors, in particular pressure sensors for an electronic tire pressure monitoring system of a motor vehicle, said sensors (9, C1, C2, C3, C4) comprising at least one module for emitting and receiving data, said method comprising: - emission (S1) of a sensor activation signal; - reception (S2) of signals coming from at least two different sensors after they have been activated; - attenuation and amplification (S3) of the signals received; - determination (S4) of a value indicative of the power of the signal for each of the signals received; - identification (S5) of the spatial position of at least one sensor on the basis of the values indicative of the power of said signals received. the reception ( S2) of signals being done during a predetermined period characterised in that said signals are attenuated in an identical manner and amplified at a fixed level.

2. Method according to the preceding claim, characterised in that the value indicative of the power of the signal is the gain value (G) and / or the adaptation value of said signal.

3. Method according to claim 1 or 2, characterised in that the signal activating the sensors (9, C1, C2, C3, C4) is transmitted at constant power.

4. Method according to the preceding claim, characterised in that the signals undergo an identical attenuation.

5. Method according to any of the preceding claims, characterised in that there is reception of a plurality of signals coming from the same sensors (9, C1, C2, C3, C4).

6. Method according to previous claim, characterised in that there is selection of the signal having the value indicative of power that is the highest for each of the sensors (9, C1, C2, C3, C4) for said identification.

7. Method according to the preceding claim, characterised in that there is comparison of the values indicative of the power of the plurality of the signals received coming from at least a first (9, C1) and a second sensor (9, C2), if all the values indicative of the power of the signals of one of the sensors (9, C1, C2) is always less than or greater than all the values indicative of the power of the signals of the other sensor (9, C1, C2), then there is identification of the spatial position of at least one of the sensors (9, C1, C2).

8. Method according to any of the preceding claims, characterised in that the attenuation level applied to the signals is variable.

9. Device (1) for activating sensors, in particular pressure sensors (9, C1, C2, C3, C4) for an electronic tire pressure monitoring system on a motor vehicle, said device being configured to implement the method according any of the preceding claims and comprising: at least one sensor activation means (31); a means (33) for receiving signals coming from the sensors; an electronic entity (35) configured for storing and / or processing information conveyed by the signals sent by said sensors (9); a means for communicating (37) with a remote electronic entity, such as the onboard computer (11) of a motor vehicle, in order to transmit the information coming from the signals received; said reception means (33) comprises: an antenna (33a) for receiving the signals coming from the sensors (9, C1, C2, C3, C4); characterised in that said reception means (33) comprises an attenuator (33b) configured for attenuating the signals received in a identical manner, an amplifier (33c) configured for amplifying signals received attenuated at a fixed level; each of the signals being characterised by a value indicative of power (G); said electronic entity (35) being configured for identifying the spatial position of at least one sensor (9, C1, C2, C3, C4) on the basis of the values indicative of the power of the signals received.

10. Device according to the preceding claim, characterised in that each of the signals is characterised by a value indicative of the adaptation undergone by each of the signals following the attenuation and amplification thereof, the value indicative of the power of the signal being the adaptation value of said signal.

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